Multimetallic articles, i.e., articles formed from a first metallic material having discrete regions therein of a second metallic material, are employed in such apparatus as magnetic clutches, brakes and the like. In certain of such apparatus, the multimetallic article forms the body of an electromagnet and comprises a ferromagnetic (magnetizable) material with regions of a nonferromagnetic material such as copper or the like therein. Usually, the electromagnet body is formed in a generally flat, annular shape which may include an annular groove therein which receives an electric coil. The nonferromagnetic material extends substantially through the entire thickness of the magnet body in a multiplicity of circular segments to provide a means for reducing radial flux leakage from the electromagnet so that optimal flux is available for the magnetic coupling of the electromagnet body to a neighboring clutch or brake plate (armature).
A well known type of multimetallic electromagnetic body comprises a flat steel plate in which segmental slots are formed by machining or the like. The slots accommodate a malleable, nonferromagnetic metal such as hammered copper which reduce radial flux leakage as described hereinabove. Those skilled in the art of such electromagnet devices will immediately recognize that such a structure, requiring both machining of the ferromagnetic plate and hammering of copper into the slots thus formed, is not only time consuming, but expensive to manufacture. Furthermore, the machined slots even though subsequently filled with copper, weaken the body to such an extent that to compensate for such weakening, the overall size of the body must be increased. This may render the body, and therefore, the electromagnet in which it is used, unsuitably bulky. While some of the bulk can be reduced by eliminating the nonferromagnetic slot fillings, such as construction may not provide the requisite reduction in radial flux leakage and also, may further contribute to the mechanical weakness of the body.
Accordingly, it is evident that an improved scheme for manufacturing multimetallic articles such as electromagnet bodies is desirable.